Histology of blood vessels and changes in vasculature in HT Flashcards
(15 cards)
Give the 3 main types of arteries
Elastic
Muscular
Arterioles
What are the main two elastic arteries? Why are they elastic?
- Pulmonary artery and aorta
- When the heart contracts, the walls of these need to stretch - allowing them to store energy
- The hydrostatic presssure that is exerted on the elastic arteries from ventricualr contraction is the systolic blood pressure
- Between heart contractions, the elastic walls recoil, to maintain blood pressure ensuring blood keeps moving even when ventricles relaxed
Name and describe the 3 layers of elastic arteries
Tunica adventitia: Has vaso vasorum, also has lots of collagen, and surrounded by external elastic membrane
Tunica media: Relatively few smooth muscle fibres and high density of elastic fibres
Tunica intima: Has an inner layer of endothelium AND surrounded by a layer of connective tissue called inner elastic membrane
Name and describe the 3 layers of muscular arteries
- Thicker tunica media, greater percentage of smooth muscles than elastic fibrs
Name and describe the 3 layers of arterioles
The tunica intima is very thin, and mostly consists of a single layer of squamous epithelium.The tunica media consists almost entirely of a single layer up to six layers of smooth muscle cells, and there is no External Elastic Lamina. The Tunica adventitia is about the same size as the tunica media layer, merges in with surrounding tissue. Interal Elastic lamina still present.
Describe factors that can result in hypertension as a result of aging.
- Firstly, blood pressure increases as we get older, this is unavoidable
- In older people, levels of inflammation are typically higher - this makes endothelial dysfunction more likely - which as a result increases the risk of athersclerossis
- Due to stiffness as a result of atherosclerosis , the arteries will not stretch as much as they should, meaning the baroreceptor reflex will not be as potent - thus blood pressure will remain high
- Neurohormonal disorders
- Renin production is decreased in elderly - therefore resulting in less Aldosterone production
The risk of hypertension increases with age, although BP is typically higher In females. This changes at around age 60, where woman can typically have higher blood pressure. Why might this be?
Reduction of Estrogen, which acts as a vasodilator.
Label these layers of the vessel
As a result of hypertension, small arteries undergo structural remodelling. One of the biggest changes that occurs is the arrangement of smooth muscle. What formation is the muscle normally arranged in?
Helical
Define Pulse wave velocity
- PWV is defined as the velocity at which the pressure waves, generated by the systolic contraction of the heart, propagate along the arterial tree
- PWV provides information about the elasticity of the arterial system
- The stiffer the vessels, the higher the pulse wave velocity
- basically you measure the time taken for the wave to travel through two points of a vessel, gives you VELOCITY
There are changes in size of the vessel components in hypertenson.
- Increased tunica media to LUMEN ratio
Summarise the results of effects on structural remodelling on leg and cerebral arteries during SIMILUATED MICROGRAVITY ON HINDLIMB UNLOADING RATS
- Basically blood pressure in head increases (so cerebal artery smooth muscle hypertrophies), blood pressure is lower in legs (so vascular smooth muscle atrophies)
- Blood
Old HT medications generally lowered blood pressure, but didn’t help vascular remodelling. GIve examples of medications that have been shown to reduce HT AND help remodel vascular muscle
A renin inhibitor has shown promise in reducing HBP as well as promoting vascular remodelling. It is thought to do this, since Angiotensin 2 - has myogenic propeties - and possibly may cause smooth muscle division. What is the name of this drug?
Aliskiren (but not really used in NHS)
